Initial re-styling of the toolbar

Move all text styles, and the remove styles button, into a new 'list' toolbar
group, using the text-styles icon. Less-used text styles (strikethrough, code
and underline) are demoted, with remove styles at the end, and bold and italic
promoted.

Now re-label the "More" catch-all to now be "Insert", which is what's left.

Change-Id: I66a1bba347ea64e540106b1090995b3117a8b1b2